Cos x/4*sin π/5-sin x/4*cos π/5=-√2/2

Cos x/4*sin π/5-sin x/4*cosπ5=-√2/2Cos x/4*sin π/5-sin x/4*cosπ/5 = -(√2)/2 ; Cos( x/4+ π/5) = -(√2)/2 ; x/4+ π/5 =  + ,-3π/4 +2π*n ; x+ 4π/5 = + ,-3π +8π*n  , n∈Z. x = (+,-) 3π - 4π/5  +8π*n  , n∈Z. x₁ =11π/5 + 8π*n  , n∈Z ; x₂ = -19π/5 + 8π*n  , n∈Z. ответ : 11π/5 + 8π*n  ,-19π/5 + 8π*n  , n∈Z.